In optical networks today, processing nodes of the networks are designed for processing various types of data frames. During the design of such processing nodes, the designed systems are tested by generating and sending through these nodes test frames. In particular, data frames comprising concatenated payloads, such as frames based on the SONET or SDH standards, are commonly used for transmitting information across such networks and accordingly, the generation of similarly structured test frames is required.
A system generating data in various frame formats will be referred herein as a data generator. The present invention considers data generators comprising one or more processing strips. Each processing strip is capable of generating a data slice of a given size. In the case when a data generator comprises more processing strips, the data slices generated by the strips are collected together in the data frame to be generated. The size of the data frame thus generated is directed to the number of data slices collected, therefore the capacity of the data generator is given by the number of processing strips it has.
Data frames comprising large concatenated payloads such as the SONET/SDH type frames may be formed by pasting together several smaller size data slices. Therefore, the generation of such frames requires the use of a data generator with enough processing strips to account merely for the size of these frames. This requirement is easily overcome by known data generators, which may be designed to the required size by including enough processing strips. A more difficult requirement to meet arises from the concatenation feature of such frames. Collecting several data slices into a concatenated frame implies synchronization of all the processing strips contributing data slices to the concatenated frames, synchronization which must take place during the generation of the actual data slices. For example, in the case of SONET/SDH type frames, the synchronization implies acknowledging the correct pointer information at all contributing strips. In addition, various overhead bytes such as the B3 byte for SONET/SDH type frames of the concatenated frame are generated only in some data slices making up the final frame, but their value is dependent on the data generated on other slices.
Similar synchronization issues are described for example in co-pending and co-assigned application Ser. No. 09/663,823 “Pointer Processing and Path BIP-8 Computation for Large Concatenated Payloads”, filed on Sep. 15, 2000, with respect to pointer processing machines structured on arrays of parallel pointer processing strips. In the described pointer processing machines, the synchronization issues are solved by establishing a bi-directional flow of data along the contributing pointer processing strips. However, such a bi-directional data flow along the pointer processing strips requires a complex design, with a large hardware overhead. For example, communicating B3 byte data only from a strip to an adjacent strip requires 9 communication pins on each strip, where 8 of these pins are for the actual B3 byte value and an extra pin is used to send a concatenation signal among the two strips.